You can access this dialog from the following:

Ribbon: OpenRail Modeling > Rail Electrification > Reference Lines

Reference lines form the basis of OverheadLine (OLE) system. They are placeholders that determine the stations where structures will be placed. All other OLE items will also be placed in reference to those lines or objects that are defined on these lines. That is structures (single, portals), wires (contact points), additional equipment, additional wire, etcetera.

Reference lines have manipulators for changing their station (manipulators for other properties are not needed).

Design standards are assigned to reference lines, all other objects read this information from the reference lines.

A reference line is always defined on a geometry and related to this main reference geometry. It can cross multiple geometries but can only have one reference geometry.

Reference lines have boxes at their ends. This is for defining the buffer zone where structures can be placed. These will be used for identifying clashes with roads, culverts, etcetera. These boxes have width and height parameters. Those parameters do not need to be modified individually for each reference line.

Range (Width) of the reference line is determined with offset from the leftmost and rightmost geometries it crosses. The offset parameter can be different for left and right and measured from the outer geometry to end of reference line (centre of buffer zone, margin box).

Reference line properties can be edited in bulk. That is the offset of the left and right ends, assigned standards, width & height of the buffers can be changed for multiple reference lines at once.

Reference lines can also be placed, at an angle (skewed, not perpendicular) to reference alignment.